Didymium difforme var. comatum Lister, J. Bot.

Lado, Carlos & Basanta, Diana Wrigley De, 2018, Typification of the myxomycete taxa described by the Listers and preserved at the Natural History Museum, London (BM), Phytotaxa 341 (1), pp. 448-450 : 448-450

Didymium difforme var. comatum Lister, J. Bot. 39: 8. 1901

≡ Didymium comatum (Lister) Nann. -Bremek, Proc. Kon. Ned. Akad. Wetensch., C. 69(3): 361. 1966 — Lectotypus (designated by Nannenga-Bremekamp, Proc. Kon. Ned. Akad. Wetensch., C. 69: 362. 1966. See below): JAPAN. Tokyo

Prefecture, Tokyo, Botanic Gardens , 35º43’N 139º45’E, Aug 1898, S. Kusano: ex dono M. Miyoshi ( BM 2462 !, BM000500872 [with two revision labels, one from Nannenga-Bremekamp and the other from Jun Matsumoto, 12 Aug 1998] + one slide BM s.n.!, 15A,

Japan, BM001089958 ). Syntypus : UNITED KINGDOM. England, Dorset, Lyme Regis , 50.725ºN 2.940ºW, Mar 1899, A. Lister (one slide L:B.M.71!, engraved 875, BM001247120 ) .

BM 2462 / Japan type/ Didymium difforme / Duby/ var. comatum Lister / Japan / BM000500872 [sheet label dated 12 JUN. 1912 “BM. 2462/ Didymium difforme Dudy / var. comatum Lister / Botanic Gardens, Tokyo, 8.1898/ leg. S. Kusano: ex dono M. Miyoshi”. Another label dated 1966: “ Didymium comatum nov. comb. / Nannenga-Bremek./ in Koninkl. Nederl. Akademie van/ Wetensch. Amsterdam, Ser. C., 69, N. 3, 1966”. On a label annotated by Jun Matsumoto in August 12, 1998: “ Didymium comatum (List.) Nann. -Brem., Proc. K. Ned. Akad. Wet. C. 69: 361, 1966./ ≡ Didymium difforme (Pers.) S. F. Gray var. comatum List., Jour. Bot. 39: 8. 1901./ Locality: Botanic Gardens, Tokyo. Date: 8, 1898. Leg.: Kusano; ex dono M. Miyoshi (BM 2462)/ This specimen is the lectotype of Didymium comatum (List.) Nann. -Brem. selected by Nannenga-Bremekamp/ (Proc. K. Ned. Akad. Wet. C. 69: 361, 1966)”] + one slide BM s.n., 15A Japan / Didymium / comatum/ Nº 15 A / Bot. Gar. Tokyo / 8.98 S. Kusano/ NXXp. 103/ BM001089958. L:B.M.71 one slide engraved 875/ Didymium / difforme/ var. ss. comatum/ List/ Lyme Regis/ leg. Lister Mar 99/ BM001247120.

NOTES: In proposing the new variety, Lister (1901a: 7) based it on the profuse capillitium and commented on several specimens: “It was found in March, 1899, growing in company with Didymium difforme Duby on old fronds of hart’s tongue fern on the Undercliff at Lyme Regis.”, and added later “Gatherings of D. comatum in April, 1900, from the Lyme Undercliff exhibited spores similar to those above described, but another gathering of the species from a straw-yard in an open field at about the same date showed profuse slender capillitium, but had spores that could not be distinguished from the normal spores of D. difforme .” and on the next page ( Lister 1901a: 8) “Beside the Lyme Regis gatherings a small specimen was obtained from near Luton in February, 1893, with profuse colourless capillitium and pale spores, precisely similar to those of the sporangia first collected on the Lyme undercliff.” Lister then cultured the specimens from spore to spore to show that the “peculiar features of D. comatum would remain constant” and obtained many sporocarps confirming the profuse capillitium even in the smallest. Lister concluded that “As far as it goes, this culture points to a specific diffrence between D. difforme and D. comatum , but in the face of the straw-yard gathering before referred to it seems safer to mark the new form as D. difforme var. comatum .”

Nannenga-Bremekamp (1966: 362–363), proposed the combination Didymium comatum (Lister) Nann. - Bremek , citing numerous specimens including some in BM “ BM 2462 , Japan type; BM 2463 , Philadelphia; …” and commented “… Specimens of syntype 2357 U, on which the description partly was based, have been sent to the B.M., …” but we did not find this. She explained the reason for chosing the “ lectotype ” (in fact a neotype, since the specimen from Japan is not mentioned in the protologue) on page 363 “This is the same as Didymium difforme (Pers.) S. F. Gray var. comatum Lister. There are two samples of this variety in the Lister’s collection at the B.M., collected prior to the date of publication (Journ. of Bot. 39: 8, 1901), but the material is very scanty, although it leaves no doubt about it being the same as the above described species. Of these two I have chosen BM 2462 as type.”. In addition, we found one slide of Lister material from Lyme Regis collected prior to the date of publication that we include as syntype .